The overall objective of the proposed research is to seek a better understanding of the role of immune processes in the pathogenesis of the chronic rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus, vasculitis syndromes, etc.) with the ultimate goal the identification of endogenous or exogenous factors that stimulate the host immune response. Multiple methods of study in numerous laboratories have demonstrated variable levels of immune complexes in patients with the above illnesses but techniques for purification and characterization of the reactants involved have not been sufficient to establish the immunochemical specificities of the relevant antigens and antibodies. New methods have been developed in the applicant's laboratory for the isolation of immune complexes which utilize Staph A receptors for IgC on killed Staphylococcus aureus. Preliminary studies (described below) of this system employing complexes of known composition have been promising. Methods applied included: 1) bulk absorption, then elution of immune complexes for physicochemical study and 2) surface labelling of trace amounts of complexes after Staph A absorption, followed by analytical study of recovered complexes. The latter technique will be particularly applicable to some clinical materials that are limited in volume or concentration, i.e., extracts of tissues, products derived from cultured tissues, cerebrospinal fluid, etc. Techniques will be monitored and refined using complexes of known specificity in order to establish optimum efficiency of recovery and preservation of nativity of immune reactants. Materials for study will be obtained from patients with rheumatic syndromes, where immunogenic stimuli are not known, and from patients with a variety of illnesses associated with immune complex formation where the etiological factors are known, e.g., infective endocarditis, HB hypatitis viral syndromes, etc.